Question

What is physical significance of sampling theorem in communication system?

Answer 1

The basis for PCM begins with the sampling theorem, which states that a band-limited signal can be represented by samples taken at a rate f_s that is at least twice the highest frequency f_m in the message signal.
The significance of sampling theorem is wideband frequency extention over standard telephone narrowband and it used in most modern VoIP and VVoIP communication products.

4) The standard frequency for speech signal in sampling theorem is 8,000 Hz